UNIT 4: LO1 (Cardiovascular System)

Question 1

What is plasma and what are its roles?

Answer 1

• Straw coloured liquid, makes up more than half of the blood
• Transports hormones, antibodies, nutrients and waste substances
• Some substances are carried by being dissolved into plasma because it is liquid

Question 2

What are the characteristics of erythrocytes and what are their roles?

Answer 2

• Bi-concave which increases the SA for diffusion
• No nucleus which allows more oxygen to be carried
• Haemoglobin contains iron which allows oxygen to be absorbed by RBCs and it gives RBCs their red pigment
• They are tiny so they can fit through capillaries
• They carry oxygen around the body

Question 3

What are the 3 types of leucocytes and what are their roles?

Answer 3

• Lymphocytes - destroy viruses and cancer cells
• Monocytes - remove dead cells and bacteria
• Neutrophils - produce antibodies

Question 4

How do leucocytes prevent infection?

Answer 4

• Phagocytosis - monocytes and neutrophils engulf pathogens
• Produce antibodies (lymphocytes) by being the complimentary shape to fit with the antigen of the pathogen

Question 5

What are platelets (thrombocytes) and what are their roles?

Answer 5

-Small fragments of cells with no nucleus
-They join together with the protein fibrinogen in order to make a web and form a clot at the site of a wound to stop blood from flowing out

Question 6

How is body temperature controlled when it is too high?

Answer 6

• Sweat is produced and evaporates from skin which is transferred into the environment
• Vasodilation - widening of blood vessels at the skin surface to increase heat loss through the surface of the skin
• Hair erector muscles relax so hairs lie flat on skin

Question 7

How is body temperature controlled when it is too low?

Answer 7

• Hairs erect to trap insulating layer of air
• Vasoconstriction - narrowing of blood vessels at the skin surface to reduce heat loss through the surface of the skin
• Shiver because respiration is needed which transfers energy to warm body

Question 8

Everything about an artery:

Answer 8

• Carries oxygenated blood at high pressure away from heart to body cells
• Small lumen
• Thick elastic tissues, outer walls and layers of muscle tissue

Question 9

Everything about a vein:

Answer 9

• Carries deoxygenated blood back to heart’s atria at low pressure
• Large lumen
• Has valves to prevent backflow of blood
• Thin layer of muscle and elastic fibres

Question 10

Everything about a capillary:

Answer 10

• Exchange surface with sieve basement membrane
• Involves both oxygenated and deoxygenated blood at low pressure - attached to arteries and veins
• Thin elastic fibres and walls (one cell thick) so increased rate of diffusion

Question 11

What is the structure of the heart?

Answer 11

• VATVAVAVVVA

Question 12

What is the function of the sinoatrial node (SAN)?

Answer 12

• It passes a wave of electrical current through the atria making them contract.

Question 13

What is the function of the atrioventricular node (AVN)?

Answer 13

• It slows down the passage of current down to the ventricles to allow them to fill with blood.

Question 14

What is the function of the purkiyne fibres?

Answer 14

• They carry the current down the middle of the ventricles to the apex of the heart causing both the ventricles to contract.

Question 15

What does an electrocardiograph (ECG) detect?

Answer 15

• It detects the electrical activity of the heart and changes in polarization in the heart by measuring the current at the skins surface.

Question 16

What do the waves on an ECG show?

Answer 16

• P - atrial systole due to electrical stimulation from SAN (atria contracting)
• P-Q - slight delay as AVN picks up electrical stimulation followed by dip as it passes down Bundle of His
• QRS - purkinje fibres pass on electrical stimulation which causes ventricular systole
• T - ventricular diastole
• U - atria fill again with blood so cycle can start again

Question 17

What is tissue fluid and what are its roles?

Answer 17

• Bathes cells of tissue, similar to blood plasma but without cells and plasma proteins
• Roles: transports oxygen and nutrients (useful) from the blood to cells, transports carbon dioxide and other waste substances from cells to the blood
• Plasma, electrolytes, glucose and urea present

Question 18

How is tissue fluid made?

Answer 18

• Blood flows into the capillary of an organ at the arteriole end of a capillary bed under hydrostatic pressure, which pushes the blood plasma out of the capillaries through tiny pores in the capillary walls (RBC, WBC and plasma proteins too big to be pushed out)
• The plasma removed is now called tissue fluid because it surrounds tissues and contains oxygen and nutrients

Question 19

What is haemoglobin?

Answer 19

It is a protein molecule that binds together with oxygen to become oxyhaemoglobin, it is what gives erythrocytes their red pigment.

Question 20

What is meant by the cardiovascular system?

Answer 20

It means that the heart pumps blood around the body which is transported by blood vessels.
- Cardio = heart
- Vascular = blood vessels

Question 21

What do the coronary arteries do?

Answer 21

They ensure that oxygen is supplied to the heart for cells so they can respire.

Question 22

What causes coronary heart disease relating to blood flow?

Answer 22

Atherosclerosis - a build up of plaque, which partially blocks blood flow (reduced size of lumen) so oxygen and nutrients struggles to get to cells so that they can respire.

Question 23

What are 3 features of a normal artery?

Answer 23

• Smooth blood flow
• Normal blood pressure
• No resistance to blood

Question 24

How is lymph fluid made?

Answer 24

• Any excess tissue fluid is absorbed by lymphatic vessels which return it to the circulatory system as lymph
• Lymphatic system (immune system) made up of many blind ending lymph vessels which allow tissue fluid to flow into them via valves
• Lymph nodes (swellings) produce WBCs which fight bacterial infections (lymphocytes)